Obviously it is none of those. Nope, I am a Republican for a few weeks just so I can vote for Ron Paul. I do not consider myself a Paul fanatic (of which there are quite a few) by a longshot. I like Paul primarily because he is the candidate most likely to end the war in Iraq, and I think that is the most important issue.
It was difficult for me to re-register just to vote for Paul. I don't like his chances of winning the Republican nomination at this point. He is obviously a huge longshot. However, the Republican party is in disarray, so I think there is a small chance. With no clear front runner, a surprise showing by Paul on Super Tuesday (California is part of that craziness now) would make a big difference.
The other factor that weighed heavily on me is that I would really like to vote for Barack Obama against Hillary Clinton. Again the issue is the war. Obama is so clearly more opposed to the war than Clinton is, that I really want him to win against her. On one hand he is a better chance of winning the Democratic nomination than Paul does of winning the Republican nomination, but I thought it was time to take a chance on a longshot.